It is desirable to steer a construction machine by rotating a front portion of the construction machine with respect to a rear portion. In order to steer the construction machine in the above described manner, it is necessary to provide two separate frames that are pinned together about a vertical axis. It is also necessary to position and attach a hydraulic cylinder between the front portion and the rear portion to obtain the desired relative rotation or articulation of the construction machine. Typically, engine and drive train components are mounted on a main frame included in the rear portion of the construction machine, and a work implement is mounted on a frame assembly included in the front portion of the machine.
In the case of some construction machines, such as, an articulated wheel loader, the frame assembly is subject to extremely high loads from several different sources. For example, the work implement is generally attached to the frame assembly by a pair of lift arms, each of which are raised and lowered by a pair of lift cylinders that extend between each lift arm and the frame assembly. The combined weight of the lift arms, the lift cylinders, and the work implement results in a substantial load being communicated to the frame assembly. The construction machine also has a mechanism that allows the work implement to be tilted with respect to the lift arms. Tilting the work implement also inputs a substantial load to the frame assembly. In addition, digging, lifting, and bulldozing operations also input a substantial load to the frame assembly.
The requirement that the frame assembly be capable of accommodating such loads inherently results in a frame assembly structure that is quite large. The large size of the frame assembly structure has several disadvantages. Specifically, the overall size, complexity, and weight of the frame assembly increases its manufacturing cost. Additionally, the operation of the construction machine may be hampered because the large size of the frame assembly (1) reduces the lifting capacity of the construction machine and (2) reduces the operator's ability to see the work implement during its use.
The present invention is directed to overcoming one or more of the problems set forth above.